DE102017004105B4 - Magnetically bistable axially symmetric linear actuator with pole contour, device with this and switching matrix for tactile applications - Google Patents

Abstract

Magnetically bistable axially symmetrical linear actuator (A) for tactile applications with a hard magnetic rod (1) which is widened at one end in a plate-like manner (1b) and with a coil (3) arranged on a circuit board in which the rod (1) is freely movable in the axial direction, characterized in that the rod (1) consists of a material with a very high coercive field strength, that it is axially enclosed by a hard magnetic sleeve (2) of at most the same length with a significantly lower coercive field strength and is freely movable in the axial direction and that the travel of the rod (1) is determined by its excess length (h) in comparison to the length of the hard magnetic sleeve (2), such that an auxiliary pole (1a) is formed at one end of the rod (1) and a plate-like main pole (1b) is formed at the opposite end and that the coil (3 - comprising several turns - completely surrounds the sleeve (2), whereby only the sleeve (2), but not the rod (1), can be reversed. and a bistable linear movement of the rod (1) is achieved.

Description

The invention relates, according to the preamble of claim 1, to a magnetically bistable axially symmetrical linear actuator. The invention also relates to devices with this for tactile applications, according to claim 5. Furthermore, the invention relates, according to claim 14, to a switching matrix for controlling coils connected in rows and columns in a device according to claim 5. Finally, according to claim 20, the invention relates to an intuitively usable optical-tactile visual aid for substituting the human sense of sight with a device according to one or more of claims 5 to 13 and a switching matrix according to one or more of claims 14 to 19.

Tactile displays (Braille lines) for displaying data from computers (PCs) for visually impaired people have been known for a long time. With the introduction of graphical user interfaces (e.g. "Windows" operating system) on PCs and the increasing popularity of screen-oriented operating systems and graphical user software, visually impaired people are calling for new types of tactile-based graphic displays. For example, one can imagine a matrix of 200x400 tactile pens on a scanning surface comparable to DIN A4. This means that the actuators required to drive the pens must be arranged close together in terms of area. Particularly in view of the growing number of mobile IT devices (notebooks, laptops, smartphones or smart watches), special attention must be paid to keeping the height of the display unit as low as possible while simultaneously using minimal energy. In particular, there is a need to provide large-area tactile display devices with a large number of individual pins (e.g. 200 x 400). For pure graphic output in particular, pin spacing of a maximum of 2.0mm is also required. Compared to the Braille cells for displaying written symbols (8 pins, spacing = 2.5mm per symbol, additional lateral space between the individual symbols), this represents a significantly higher requirement.

Due to the complex conditions when using tactile Braille lines, piezo drives for the pens have become established on the market. The very expensive ceramic actuators, which usually work as bending elements, require additional mechanical force deflections in order to even realize a pen movement perpendicular to the scanning surface. In combination with the high voltage required to control the actuator, this results in an extremely high price level, especially with regard to surface displays. The latest estimates for the price of a tactile surface display (7600 pens) are in the order of magnitude of the annual salary of a very well-paid employee.

The mechanical, electrical and price disadvantages of the established piezo modules have also led to the fact that to this day there is no "barrier-free" access for blind people in the entire self-service area. Whether it is ticket machines with graphic route displays, drinks machines or cash/bank machines: blind people have no chance of using these devices discreetly because there is usually no suitable tactile output medium built in.

In connection with the minimum forces required (e.g. 0.3N) for a reliable scanning process by the sensing finger, small pin spacing is a fundamental problem, since with all axial actuator types a sufficient amount of functional material must be attached in the vicinity of the tactile pin - in this case, for example, with the magnetic actuator, this primarily means a coil with a large number of wire turns. The simple arrangement of all axial actuators of the tactile display in one plane (parallel to the plane of the stylus) is therefore not possible for spatial reasons.

The problem of tight spacing also applies to the mostly electrical control of the actuators. This is particularly critical in piezo applications, as high-voltage electrical modules are used. Ultimately, all actuator types require a considerable area to accommodate the integrated circuits (ICs). This is usually solved by attaching the ICs to the side next to the actuator surface, making the display less compact overall.

Due to the current market situation for tactile displays, the following discussion can focus on piezo-ceramic actuators. This technology currently represents the state of the art in this field, as shown by a preliminary study on the "HyperBraille" project (report by the Federal Ministry of Economics and Technology, 10115 Berlin, April 2010, www.bmwi.de).

For large-area displays, the actuators must be arranged very closely together. Piezo solutions therefore have a considerable height due to, for example, complicated stacking techniques for several circuit boards, which means that piezo technology is not very attractive, especially for mobile applications - not least because of safety aspects in connection with the high electrical voltage (> 100V) required to control the actual bending elements.

The main disadvantage of any piezo solution is that at least one stable pin position ("up" or "down") can only be achieved through permanent electrical control. In the energy-saving "off" state of the entire display, valid display of the data is therefore not guaranteed.

The majority of tactile displays use piezo actuators, with all their resulting disadvantages (high price, large installation heights, permanent high electrical voltage, additional mechanical devices for power transmission), such as in EN 103 49 100 A1 for a 10-pin surface module. The problems of piezo actuators when used in surface displays, especially the mechanical and electrical requirements, are discussed in the EN 103 49 100 A1 by complex stacking processes of a large number of individual circuit boards. When used in conjunction with tactile pens, the actuator must have a clearly defined “up” and “down” position and a sufficient holding force (e.g. 400 mN). EN 103 49 100 A1 A piezo surface solution is also offered, but the use of additional mechanical elements (knee lever gear) again shows the fundamental difficulty of ensuring a clear, clearly palpable "up" or "down" state of the pin. The device for mechanical power transmission alone takes up a considerable amount of geometric space, and the spatial accommodation of the control ICs and connectors to a bus system pushes the height even higher in the vertical direction.

EN 10 2010 005 933 A1 also shows this problem here, in addition to the use of a wedge gear for resetting the pins, gravity is even relied upon, which, against the background of mobile applications, is fraught with problems with regard to the correctness of the data display.

US 2010/0085168 A1 presents a planar arrangement of linear actuators, ie a planar arrangement of individual piezo elements parallel to the pin plane, but refers explicitly to linear piezo actuators, leaving completely open how the rather considerable necessary tactile stroke of approx. 0.7 mm can be technically realized. The difficulty of achieving small pin distances (less than 2.5 mm) is already clear from the illustration there (1). In the US 2010/0085168 A1 At no point is it discussed how the required minimum forces can be achieved in connection with the dimensioning of the piezo components.

In EN 10 2007 022 056 A1 An attempt is being made to create a surface display under realistic conditions (with regard to forces and spatial dimensions of the piezo actuators). A large number of circuit boards are required, but only an edge area is used to accommodate the piezo actuators. The assembly of the entire display is complex and results in a device height that is unacceptable for mobile applications, for example.

A surface display equipped with magnetic actuators, in particular a display approach for mobile solutions, shows DE 198 27 666 A1 , where electromagnetic actuators are mentioned alongside piezo actuators, but here the pins are only controlled line by line, by an additional control car that is moved mechanically. The magnetic version shown also contains a large number of additional mechanical locking and lever devices. Accordingly, the problem of the large space requirement of the control coils is solved here by the magnetic actuators from the mechanically moved control car only setting the pins to the "up" or "down" position line by line. Fast electrical individual addressing of the pins - as is absolutely necessary for graphic PC applications - is by no means possible here.

A fundamentally similar approach is used in EN 10 2014 011 326 A1 described. Here too, the positions of a tactile surface display cannot be addressed individually and a multitude of mechanical guide, holding and repositioning elements are provided to achieve a stable top/bottom position of the tactile pins. The description also highlights the as yet unsolved problem of using electromagnets in a tactile environment (typical grid approx. 2.5mm). The solution presented is also definitely not suitable for a compact - perhaps even mobile - tactile surface display device.

In the US Patent 4,259,653 A1 A bistable linear actuator with permanent magnets is presented. However, the "up position", which is particularly important for tactile applications, is the least stable (lowest force in the system) and when the coil is switched off, the system immediately falls into the "down position", which means that a reliable representation of the data in the electrical "off" state of the display is no longer possible.

Also one in the US 4 831 372 A The magnetically operated information display device described works in principle in an electromagnetically bistable manner, but here no forces are transmitted to the outside, only a partition wall is moved inside a closed optical display cell. Here too, a wealth of additional guide and end stop elements are required. More specifically, the information display device includes a rigid, permanently magnetized display segment movably mounted in a non-magnetic chamber having a transparent viewing window and containing an opaque fluid whose color contrasts with the color of the display device. A core attached to the back of the chamber is capable of being selectively magnetized to repel or attract the display segment according to the selected magnetic polarity of the core. Repulsion of the display segment by the core causes the display segment to move toward the transparent window through which the color of the display segment can be viewed when the opaque fluid is displaced away from the transparent window. Attraction of the display segment by the core causes the display segment to move away from the transparent window, allowing the opaque fluid to interfere with viewing of the display segment. In this position, the color of the opaque fluid is viewed through the transparent window. The bistability of the magnetically actuated information display device is achieved by the residual magnetism in the core acting on the permanently magnetized display segment, minimizing the duration and amount of energy that must be applied to initiate a change in the display of information. A plurality of display devices can be combined in an array to form a display panel with improved resolution of the displayed image.

Magnetic linear actuators are also used in US$3,755,766 and US$4,072,918 described. The problem of the stable end position is solved here by additional spring systems. However, these springs prevent the system from reacting quickly to control signals (in the opposite direction), weaken the "top holding force" and make the structure even more complicated. In order to deal with the force problem, soft magnetic flux guide devices are also required, which means that the actuator is neither compact nor inexpensive to manufacture.

Especially for mobile tactile display in braille symbols, EP0925570B1 a micro electromagnet is described. Here too, it is characteristic that energy must be permanently supplied to at least one end position of the coil, and leaf springs and O-rings are used for resetting.

In US 5,466,154 A The problem of continuous current supply and achievable tactile forces (here only 50 mN) in previous electromagnetic solutions is clearly demonstrated in a Braille plate with movable point pins. In the solution presented there, the Braille plate with a microprocessor and a large number of solid-state switching chips, whereby each of the actuators is selectively operated under the control of the microprocessor and a chip controller to translate the alphanumeric information, either a hard magnetic rod is moved using air coils or an air coil with a field-enhancing iron core, i.e. completely normal "conducting iron" without any further magnetic specification, is used. In the "top position" permanent current supply is therefore required so that when current is applied with 10 mA a maximum force of 50 mN is achieved. If we assume that tactile surface displays have 10,000 pins, of which an average of 5,000 would need to be permanently powered, we arrive at a current requirement of 50 A even for this low force of 50 mN. This explains, among other things, why the use of piezo technology defines the state of the art.

DE 102 60 668 A1 has a plate-shaped armature, but also uses additional springs to realize the “up” position.

In DE 102 34 863 A1 An electromagnetic button with tactile feedback is described. In addition to the continuous current supply to the coil, an additional spring element is also required for movement and end position fixation of the hard magnetic inner core.

The primary approach of EP 1 681 687 B1 is the highly complex development, manufacture and use of magnetic composite materials to optimize external field progression depending on the micro/nano-magnetic structure of these new materials. Despite this considerable inventive effort - the cost consequences of which cannot yet be determined - the presented embodiment of a bistable linear actuator unit with two hard magnetic materials of different coercivity for the special case of a "braille application" shows the disadvantages known from the state of the art: (at least) two movable hard magnetic bodies are arranged one behind the other. The "top" and "bottom" positions are not clearly defined here, which does not play an important role given the declared focus of the device on suspension technology applications, but is essentially disadvantageous for tactile applications. In addition, it is clearly shown that in order to maintain the "top" position, a permanent current flow through the additionally moving excitation coil is required due to the design.

All of the electromagnetic solutions presented have in common that no Information on the geometric design of the pole shapes (eg contours or aspect ratios) is provided, which address the special requirements of tactile surface displays. In addition, solutions using “memory metals” are also discussed (see eg Haga, Makishi et al. al, in Sensors and Actuators A, Vol. 119, 13 April 2005, pp. 316-322 ). However, the temporal response of these configurations does not meet the requirements of fast addressability.

For closely arranged tactile pins in braille displays and graphic surface displays, a mechanically and structurally simple and inexpensive bistable electromagnetic linear drive unit is to be provided in which the "up" and "down" positions are mechanically clearly defined. This should be done without additional holding, lever and damping devices and allow a low overall height of the later overall display. In particular, the holding force and holding position of the "up" position should be adjustable according to the tactile requirements using simple design measures. With regard to mobile applications in particular, the actuator should be particularly energy-saving and retain the correct display of the last computer data even when the entire device is electrically "off". For the large-scale display of graphic content, the unlimited close (= grid spacing less than or equal to 2.5 mm) surface arrangement of the individual actuators must be guaranteed. Interference and coupling between the individual actuators must be minimized.

The trivial boundary condition of such a computer display is of course the ability to quickly address each tactile pin individually (similar to a "random access memory"). Furthermore, it should be possible to position a large number of vertically moving pins over a large area at a predefined narrow grid spacing so that the desired narrow grid spacing of the pins can be achieved despite a lateral dimension of the individual drive unit that significantly exceeds the actual pin grid dimension. The mechanical power transmission and electrical supply of the actuators must be implemented with a minimal height of the display.

With the increasing use of screen-oriented operating systems and graphical user software, there is a need to provide large-area tactile display devices with a large number of individual pens (e.g. 200 x 400). Due to the large number of individual pens, the flawless function of the individual tactile pen over a long period of use is a prerequisite for guaranteeing the flawless function of the display as a whole. This means that - from the point of view of error statistics alone - significantly increased requirements arise with regard to the reliability of the function of the individual pen.

A lack of robustness and short service intervals are also a major reason why tactile displays have so far hardly found their way into public spaces. To date, there is practically no "accessibility" for blind people, for example in the entire self-service area: be it ticket machines, drinks machines or cash/bank machines: the blind person has no chance of using these devices discreetly because there is usually simply no reading unit built in that is suitable for them.

Regardless of the type of actuator used, the end user's main concern is the easy readability of the display - this means the highest possible minimum actuating force (e.g. 0.3N) for a reliable scanning process by the tactile finger - and above all the reliability of the entire device. The main source of malfunctions, however, is contamination, which arises solely from the nature of the tactile process when reading or entering data: grease, skin particles, hair and sweat are brought in directly by the person using the display. Dust, moisture and accidental wetting of the display with liquid do the rest to cause a service case sooner or later.

One way to minimize external influences is to place foils on the tactile surface, as in DE 101 27 039 B4 described. The disadvantage here is that the elevation of the stylus is less pronounced compared to the display level, making reading the tactile information more difficult and less reliable. For this reason, display covers have not been adopted in practice.

The alternative to covering the top of the display is to seal the individual pin in its guide, as in DE 103 06 230 B4 This method is fundamentally critical, particularly in connection with the usually low actuating forces of the actuators. It also makes the structure of the unit more complicated, and a simple removal of the individual pin - ideally by the visually impaired end user himself - is not conceivable with the embodiment shown.

In order to resolve a contamination problem in the pen area, the end user usually has to send the entire tactile display to the manufacturer for cleaning. DE 37 06 286 A1 therefore proposes a display with a completely replaceable reading pen unit that can be separated from the piezo actuator part as a whole. In this way, in the event of servicing, the actuator part can remain with the end user, who can then only continue to work with the display by means of a complete reserve pen unit that has to be purchased separately. The disadvantage here is that if just one pen malfunctions, the entire pen unit has to be removed, because the pens themselves are expressly built into their unit so that they cannot be lost - i.e. they cannot simply be removed by the end user themselves - and buying the reserve pen unit naturally incurs additional costs. In order to guarantee the force coupling between the actuators and the actual tactile pens, and to enable the entire pen unit to be replaced, holding magnets are attached to the undersides of the reading pens, which interact with the ferromagnetic material on the free ends of the activators. In addition to additional material costs and complex precision engineering assembly work in the manufacture of the display, the dynamic load on the actuator/pin system caused by the increased total mass of the hard magnet is a critical factor with this special arrangement of the magnetic material. In addition, the property of creating a mechanical fit through the connection does not come into play with this arrangement of hard magnetic and soft magnetic material, because the flat design of the magnet at the end of the pin described above can result in additional transverse forces if the mechanical fit is inaccurate, which hinder both the pin and the actuator from moving freely vertically.

Consequently, the subordinate claims also point out the need for additional catches to ensure the fit between the module body and the reading pen unit as a whole. This also makes it clear that considerable effort will be required for the mechanical precision (tolerance problem) of the two complex parts. The magnetic coupling shown with a flat permanent magnet at the end of the pen therefore does not fulfil the task of reliably adjusting the individual pen without the application of transverse forces without additional mechanical devices.

For tactile pens, a simple and inexpensive way should be created to minimize the negative effects of the omnipresent sources of contamination on the proper functioning of the individual pen, without this measure affecting the tactile quality of the display. In the event of servicing, each individual pen should be easy to remove/clean and re-use without any problems, and if possible even by a clumsy, visually impaired end user.

The congruent transfer of the use of graphical user interfaces to the use area of visually impaired people on the PC also requires the interactive, intuitive usability of the tactile display as an input unit, i.e. a bidirectional mode of operation. In the subject of the above-mentioned EN 103 49 100 A1 The individual circuit boards must also be wired together for electrical control. In the overall device, the actuator arrangement described also works exclusively passively as a display device. In order to be able to implement inputs for controlling the entire device, additional actuation switches are required, which not only increase the space required but also the electrical wiring effort.

Furthermore, the US 2005/0158695 A1 a tactile display device is known in which the image information is displayed as height differences between tactile pins driven crosswise in a matrix arrangement and in which a guide plate with frictional engagement for the tactile pins is arranged below the plane of a pin plate.

Furthermore, the JP2004-7101677-A a tactile display device is known in which the actual tactile stylus is firmly connected at one end to an actuating rod whose diameter is smaller than the diameter of the actual stylus. The actuators that control the protrusion or retraction of the stylus are controlled by a movable unit that can move vertically and horizontally at high speed, so that a sharp tactile display with high resolution can be achieved.

A pure input device with haptic feedback of a key press via coils and moving magnets describes EN 10 2010 012 247 A1 . In subclaim 6, reference is made to a matrix-like circuit with connection of coils to at least one multiplexer. The term "input device" alone makes it clear that the structure in the form described cannot under any circumstances be used as an output unit (e.g. as a tactile graphic display).

The same purely passive functionality is also shown EN 10 2014 104 633 A1 , where two coils are coupled in pairs, matrix-connected to form a coil field.

An economical matrix connection of signals also describes EN 10 2004 055 939 B4 . The selection is made here via electrical blocking elements in the electrical lines in conjunction with other capacitive elements, which is prohibited from the outset in the tactile application dealt with in this application due to the coil current supply via an applied direct voltage. From an electrical point of view, this matrix circuit also only works in one direction.

A matrix sensor element is also available in DE 10 2010 000 669 A1 described. The application focused there relates to room detectors installed in the floor for detecting people. This device, which also only works in a unidirectional direction, uses the change in the natural frequency of oscillators as useful information, so it requires additional capacitive components in addition to the coils.

There are a wide range of optical vision aids available for people with severe visual impairments, which usually provide assistance by magnifying and increasing contrast. For people who are completely blind, this type of device is naturally of no help at all. The use of acoustic aids does help with "reading out" text, for example, but does not provide the blind person with any additional graphic or optical information. Conversely, people with severe visual impairments generally have very good tactile sensitivity in their fingertips, usually due to intensive training in reading Braille characters.

For this reason, tactile displays for the output of data from computers (PCs) for visually impaired people are widely used as so-called "Braille lines". Large-area tactile graphic displays with a large number (e.g. 250 x 400) of tactile positions are now technically feasible. The first examples of such displays are now being presented as prototypes for stationary applications at relevant trade fairs.

• Erschließung der visuellen, durch die Sehbehinderung nicht direkt zugänglichen Domäne, unter Einsatz der eigenen taktilen Fähigkeiten und eines hierfür maßgeschneiderten neuen Hilfsmittels. Entscheidend zur Durchsetzung am Markt wird die intuitive Nutzbarkeit des Gerätes sein: es wird erwartet, dass praktisch ohne zusätzliches intensives Training der unbewusste Ablauf des „normalen“ menschlichen Gesichtssinns als Ganzem mit fovealem und periphärem Sehen auf taktiler Ebene simuliert werden kann und die Sehhilfe dabei auch mobil einsetzbar ist.

Especially in view of the generally high level of tactile competence of users of tactile graphic displays or standard Braille lines, the call for a universal (= not only limited to text templates) mobile tactile visual aid for the blind is becoming louder:

• Access to the visual domain that is not directly accessible due to the visual impairment, using one's own tactile skills and a new aid tailored to this purpose. The intuitive usability of the device will be crucial to its success on the market: it is expected that the unconscious process of the "normal" human sense of sight as a whole with foveal and peripheral vision can be simulated on a tactile level with practically no additional intensive training, and that the visual aid can also be used on the move.

The first attempts to convert optical structures into information that can be felt by the blind with significant spatial resolution are described in DT 2330403 A1. Here, a planar contrast structure is transferred into an analogue electrical charge pattern matrix with a specific, design-related lateral resolution using a contact method, i.e. without lens-optical imaging. The human skin is proposed as a sensor for this information, with the forehead being the preferred contact surface due to the flat construction of the charge carrier matrix. Apart from the very limited lateral resolution of this method, this "seeing with the skin" involves considerable training over many years. The reliability of the method (e.g. the problem of electrical charges in high humidity) is also doubtful. In addition, due to the lack of imaging lens elements, no real image of the 3-dimensional real environment is available. A "tactile interaction monitor (TIM) is used in DE 42 41 937 A1 presented. According to the applicant, this more theoretical device concept is based more on "... philosophical, linguistic, semiotic and cognitive science research work..." and offers no concrete indications for practical technical implementation by the average expert. Due to the state of the art at the time (1992), a large number of small tactile dot grids (typically with a maximum of 256 points per matrix) are used. The grid elements (some are basically just shortened standard Braille lines) are permanently assigned to the palm of the hand or the fingers of the blind person for scanning purposes. Despite the use of a camera / scanner, a seamless, continuous tactile representation of an image of the environment is by no means possible. An attempt is made to compensate for this disadvantage essentially by a zoom and crop function of the device. This is precisely where the biggest disadvantage of the TIM lies: the complicated control of zoom and crop requires a large number of additional function keys, which are more or less parallel to the actual tactile "vision process". must be operated. The human short-term memory mentioned in the text with a storage time of max. 8 seconds is therefore completely overwhelmed when operating the TIM. Even the presumably 2 years of additional training for successful orientation in the real environment with the device, admitted by the applicant, changes little in the basic facts of the brain's physiology. It simply shows that the TIM is certainly not intuitive to use, a parallel tak A physical substitution of the “normal” sense of sight cannot take place under any circumstances.

The use of a camera mounted in a glasses-like construction is used in EN 10 2005 000 820 A1 described. However, this mobile arrangement is specifically intended to improve the vision of a person who is only visually impaired and consequently uses purely optical methods for image output. There are no tactile devices provided, which are indispensable in an aid for completely blind people.

Out of ABID, SH: New Haptic device to use Computers for blind persons. In: Al-Mansour Journal, 2012, 18th vol., no. 1, pp. 41-50 A tactile display is known in which a magnetic rod is moved linearly by applying a voltage to a coil.

Furthermore, a similar tactile display, in which a magnetic rod is moved linearly by applying a voltage to a coil, is known from the EN 10 2005 047 837 A1 The tactile display has a tactile input device which comprises an electrode which is provided on a surface of a cover plate. This electrode comprises narrow and closely spaced conductor tracks which together form a capacitor plate. In detail, a frame of the graphic display is provided which accommodates a matrix arrangement of display units. Each of the display units comprises two columns of display pins which can be displaced in a direction perpendicular to the surface of the display in order to display a tactile image of a computer output there, e.g. a line drawing, a bar chart, a marking for a tactile input field, etc. Each of the display units has an upper cover plate which has two rows of five guide holes each for the end of a display pin. Behind the upper cover plate there is a middle housing plate which is provided with guide holes which represent an aligned continuation of the guide holes. The display pins are connected to rod-shaped output parts of servo motors which have a cylindrical housing with the same diameter as the display pins. In practice, the actuators can be electromagnetic actuators, actuators operating on the moving coil principle, linear synchronous motors, combinations of a small electric motor and a rack and pinion drive or similar, or fluid actuators. The actuators can move the indicator pin connected to them between a rest position retracted behind the upper cover plate and a working position protruding above the top of the cover plate. In order to be able to provide tactile feedback to a computer connected to the display at each pixel of the display, the actuators are supported by a force sensor and a circuit board on a lower end plate of the display unit. The actuators are arranged so that they can be moved in the guide holes, so that a tactile feedback force exerted on the associated indicator pin presses the lower end of the actuator against the force sensor. Under these conditions, the force sensor generates an output signal that allows the tactile feedback to be recognized.

Furthermore, a similar tactile display, in which a magnetic rod is moved linearly by applying a voltage to a coil, is made of BOWLES, A., et al.: A new technology for high density actuator arrays. In: Smart Structures and Materials 2005: Smart Structures and Integrated Systems. SPIE, 2005. pp. 680-689. doi: 10.1117/12.598455 Primarily intended for the tactile display of general-purpose text, Braille and graphics, magnetic forces are used to actuate and hold individually addressable pins. Using multilayer printed circuit board techniques to minimize production and assembly costs, large arrays of magnetic solenoid actuators have been fabricated on a single substrate. These are electrically interconnected to enable matrix addressing of each individual element in the array and to reduce the number of electronic components. Using a permanent magnet layer, a bistable mechanism is fabricated that allows the solenoid actuator to be switched between an "up" state and a "down" state. This bistability is not only necessary for matrix addressing, but also provides good energy efficiency, as power is only required when the system is being updated, not when the static display is being maintained. An error correction technique is also provided that automatically corrects a bistable actuator if it has inadvertently moved to an incorrect position due to a mechanical shock.

Finally, in the technically distant field of consumer electronics, namely video recorders with helical scan, US6,222,705 B1 a rotary magnetic head device consisting of a rotary drum and a thin film magnetic head is known. The magnetic head projects diametrically from the rotary drum to come into contact with a wound magnetic tape and around a part of the outer peripheral surface of the rotary drum. Furthermore, head control means are provided for adjusting the projection of the magnetic head in the diametrical direction.

Compared to the known linear magnetic actuators, the invention is based on the task of providing such an electromagnetic actuator for tactile applications, in particular for tactile pens in braille displays and graphic surface displays, with which a mechanically simple and inexpensive bistable electromagnetic linear drive unit can be realized. Furthermore, the actuators should be used to create a display with a minimal height. Furthermore, the penetration of dirt particles into the interior of the actuator should be minimized. Furthermore, a simple and inexpensive arrangement for the electrical wiring of electromagnetic actuator coils should be provided, which allows the tactile display to be used exclusively by means of the existing actuator coils to output data as an input unit, without the need to install additional input switches or other input sensors. Finally, the blind should be provided with a device that offers them the most perfect possible substitution and simulation of the "normal" human sense of sight on a tactile level.

This object is achieved according to the invention in an actuator according to the preamble of patent claim 1 by the features of the characterizing part.

In the actuator according to the invention, the hard magnetic polarized rod, which is designed as a specially shaped plate at one end, is movably arranged inside the hard magnetic sleeve in such a way that the plate itself is always positioned outside the sleeve. The coercive field strength of the material of the sleeve surrounding the rod is significantly lower than that of the movable rod. This ensures that the sleeve can be specifically reversed by the energized coil that encompasses both hard magnets (rod and sleeve), but that the polarization of the movable rod is not changed by this. The maximum current for the coil only has to be provided for the brief moment of the actual remagnetization (< 1 µs) of the sleeve material. The end position "top" provides the maximum holding force and is realized by the magnetic attraction between the specially shaped plate (= "main pole", armature) and the suitably dimensioned end face of the surrounding sleeve. This front surface is dimensioned in such a way that it provides the required holding force in conjunction with the specially shaped main pole, but is set up in such a way that it can be overcome in the event of a switchover (sleeve and coil current reversed) and the armature can thus move to the other end position. The geometric position of the "bottom" end position is clearly defined by the total length of the rod and thus the distance of the "auxiliary pole" from the armature.

Furthermore, this object is achieved in a device for arranging axial actuators according to claim 1 for tactile displays with a pin plate and pins, according to claim 2 in that the actuators are arranged in at least two and a maximum of four planes running parallel to the pin plate of the display and staggered vertically in such a way that the lateral mutual distances of the actuators in one plane are greater than the grid dimension specified for the pin plate.

The device according to the invention enables the realization of a display with a minimal height in a surprisingly simple manner, whereby the individual axial actuators are arranged two-dimensionally - offset parallel to the pin-plate plane with pins of the surface display. The working direction of the individual actuators and the plane of the pin-plate are perpendicular to each other.

In a further development of the invention, according to claim 3, the main pole has the contour of a cone or a truncated cone or a truncated cone with a disk-shaped base as a plate-like extension, wherein the height of the cone or the truncated cone or the height of the plate-like extension of the rod means that the stray field of the plate-like main pole in the "down" position of the actuator is no longer able to switch the magnetization of the sleeve.

This further development has the advantage that the spatial extent of the stray field can be influenced in a simple manner, so that a close (= grid spacing less than or equal to 2.5 mm) surface arrangement of the individual actuators in a Braille display and/or graphic surface display can be ensured.

In an embodiment of the invention, according to claim 11, a mechanical dirt shield is arranged below the plane of the pin plate for reliable operation of the movable stylus pins, which minimizes the penetration of dirt particles into the interior by geometric shading.

This design has the advantage that it is now possible to minimize both the size spectrum and the amount of dirt particles deposited in the vicinity of the actuator. Because a geometrically designed dirt shield is installed under the guide of the individual pin in the pin plate, acting device is installed, the actual actuator is shielded from dirt. The manufacturing difficulty of ensuring high-precision mechanical fits between the pin plate and the actuator is avoided by coupling the pin to the actuator via a detachable magnetic connection, which geometrically adjusts itself during the first assembly process in the production of the display. For later servicing, there is the additional advantage that the end user can remove the individual pin from the outside of the display (with the help of a very simple gripping tool or fingernails) and then use a targeted cleaning to make the affected individual pin itself and its guide surfaces functional again.

In a further development of the invention in a switching matrix, according to claim 14, for controlling coils connected in rows and columns in a device according to claim 5, the coils each have a hard magnetic axially movable core inside, and thus the individual coil can function both passively as a sensor via electromagnetic induction by mechanical displacement of the hard magnetic core, and mechanically actively as an actuator by means of targeted current supply to the coil.

This further development has the advantage that a simple and cost-effective arrangement for the electrical wiring of electromagnetic actuator coils is provided in a simple manner, which allows the tactile display to be used exclusively by means of the already existing actuator coils for outputting data as an input unit, without the need to install additional input switches or further input sensors.

An example of an intuitively usable optical-tactile visual aid for substituting the human sense of sight is the primary optical image information of a camera, which is designed as an area sensor or line sensor and, after undergoing software-based image processing for the purpose of data reduction and image recognition, is fed to a large-area tactile display device, with the number of tactile grid points being at least 50 x 80 = 400. This has the advantage that the existing tactile abilities are sufficient in a simple way to substitute the display and warning options of the visual sense purely intuitively, i.e. without using additional cognitive control and monitoring functions, on a large-area tactile dot grid (typically at least 80 x 100 points). What is particularly important here is the evolutionary architecture: transferring conscious vision (with high resolution) versus unconscious but fast peripheral vision (with low resolution) into the tactile domain. The training effort does not exceed the usual effort required to get used to a new tactile aid.

• 1a bis 1d verschiedene Funktionsphasen einer ersten Ausgestaltung des erfindungsgemäßen magnetisch bistabilen axialsymmetrischen Linear-Aktuators,
• 2a bis 2e fünf weitere Ausgestaltungen des Linear-Aktuators gemäß der Erfindung,
• 3 die Ausgestaltung gemäß 2d in einer weiteren Funktionsphase,
• 4 das Diagramm aus Haltekraft und Gegenkraft für verschiedene geometrische Kombinationen in Ausgestaltung des Linear-Aktuators gemäß der Erfindung,
• 5 die Ausgestaltung eines Displays mit zwei Aktuator-Ebenen gemäß der Erfindung,
• 6 das Lochmuster des Displays nach 5,
• 7 das Prinzip des Raster-Besetzungsmusters für eine Ausgestaltung eines Displays mit vier Aktuator-Ebenen,
• 8 eine Schrägbild-Skizze der gesamten Stapel-Anordnung für das Display mit 4 Aktuator-Ebenen nach 7,
• 9 eine Darstellung zur Verschmutzungs-Situation bei einem taktilen Display,
• 10 die Verschmutzungs-Situation bei einem taktilen Display mit einer Schmutzblende und beweglichen Taststiften und magnetischer Ankopplung mit Selbstjustierung gemäß der Erfindung,
• 11 das Einsetzen oder Entfernen eines beweglichen Taststifts für eine Vorrichtung/ taktiles Display nach 10,
• 12 die Verschmutzungs-Situation für eine zweite Ausgestaltung eines taktilen Displays mit einer Schmutzblende und beweglichen Taststiften und magnetischer Ankopplung mit Selbstjustierung gemäß der Erfindung,
• 13a, 13b die Verdeutlichung der Selbstjustierung für die Displays nach 10 bis 12,
• 14 den Aufbau und die Beschaltung einer Spulen-Matrix für die aktive Aktuator-Funktion gemäß der Erfindung,
• 15 die Spulen-Matrix nach 14 im hochohmigen Eingabezustand der Vorrichtung.
• 16 die Block-Anordnung einer intuitiven Sehhilfe mit einem Flächendisplay mit konstantem Rasterabstand der taktilen Punkte gemäß der Erfindung,
• 17 eine Ausgestaltung mit einem Flächendisplay mit geometrisch nicht einheitlichem Punktraster,
• 18 eine Ausführungsform mit einer Anordnung von Kamera Datenverarbeitung und taktiles Display in einem Gehäuse,
• 19 eine Ausführungsform mit eingebauter Zeilenkamera / Scanner
• 20 eine Ausführungsform als mobile Variante, insbesondere Smartphone.
• 21 die Ausführungsform nach 20 in Seitenansicht und
• 22 eine weitere Ausführungsform der mobilen Variante.

Further advantages and details can be found in the following description of preferred embodiments of the invention with reference to the drawing. In the drawing:

• 1a to 1d various functional phases of a first embodiment of the magnetically bistable axially symmetric linear actuator according to the invention,
• 2a to 2e five further embodiments of the linear actuator according to the invention,
• 3 the design according to 2d in a further functional phase,
• 4 the diagram of holding force and counterforce for various geometric combinations in the design of the linear actuator according to the invention,
• 5 the design of a display with two actuator levels according to the invention,
• 6 the hole pattern of the display 5 ,
• 7 the principle of the grid pattern for a design of a display with four actuator levels,
• 8th an oblique sketch of the entire stack arrangement for the display with 4 actuator levels according to 7 ,
• 9 a representation of the contamination situation on a tactile display,
• 10 the contamination situation in a tactile display with a dirt cover and movable styluses and magnetic coupling with self-adjustment according to the invention,
• 11 the insertion or removal of a movable stylus for a device/tactile display after 10 ,
• 12 the contamination situation for a second embodiment of a tactile display with a dirt cover and movable styluses and magnetic coupling with self-adjustment according to the invention,
• 13a , 13b the clarification of the self-adjustment for the displays after 10 until 12 ,
• 14 the structure and wiring of a coil matrix for the active actuator function according to the invention,
• 15 the coil matrix after 14 in the high impedance input state of the device.
• 16 the block arrangement of an intuitive visual aid with a surface display with constant grid spacing of the tactile points according to the invention,
• 17 a design with a surface display with a geometrically non-uniform dot grid,
• 18 an embodiment with an arrangement of camera data processing and tactile display in one housing,
• 19 a version with built-in line camera / scanner
• 20 an embodiment as a mobile variant, especially smartphone.
• 21 the embodiment according to 20 in side view and
• 22 another embodiment of the mobile variant.

In 1a To illustrate the purely magnetic mode of operation, a view of the arrangement according to the invention is shown in the “up” position of the rod 1. In this and the following illustrations (see 1b , 1c , 1d ), for reasons of clarity, only a rectangular cross-section of the axially symmetric poles is initially used. The linearly freely movable hard magnetic rod 1 slides in the also hard magnetic sleeve 2.

The stable "up" position is shown, in which the coil 3 is not energized. The plate-shaped main pole 1b ensures that the "up" position of the rod 1 is spatially clearly defined and maintained with maximum force. The thickness of the main pole 1b is designated "H1". The protrusion of the auxiliary pole 1a is designated "h" as the difference to the length of the sleeve 2. The axial magnetization directions present in both materials are marked by arrows. The representation of the magnetization directions should be viewed as a schematic diagram.

1b shows the transition phase from the "up" to the "down" position, in which the sleeve 2 is already reversed by the magnetic field of the now energized coil 3 (as illustrated by the dots and crosses in the wire cross-sections). The thick vertical arrow indicates the downward movement, the magnetization shown can be seen schematically, as already in the description of 1a was executed.

1c shows the stable "down" position of the rod 1, also with the coil 3 de-energized and the magnetization directions marked by arrows. In this position, the upper end 1a of the rod 1 serves as an auxiliary pole, which realizes the "down" position of the entire rod 1 in terms of force and position. The thickness H1 of the armature is used to control the spatial strength drop of the magnetic field of the main pole 1b on its upper side (demagnetization fields inside the pole). The field strength is set up in such a way that in the "down" position of the rod (see 1c ) no remagnetization of the sleeve material can occur due to the stray field of the armature 1b and the position is therefore geometrically and force-wise stable.

To realize the upward movement of the rod 1, the coil current then flows in the opposite direction, with now reversed magnetization of the sleeve 2 and correspondingly reversed force direction, as in 1d The thick arrow now indicates the upward direction of movement.

The technical implementation shows the transition from 1a (unpowered, stable position “above”) to the situation in 1b (just remagnetized sleeve 2 with energized coil) is particularly critical because the requirement for a high "up" holding force of the actuator on the one hand and a separation of the plate 1b from the sleeve 2 with acceptable coil currents (e.g. under 3 A) on the other hand, two opposing phenomena are involved: a high holding force requires a strong attraction between the main pole 1b and sleeve 2, while the easy detachability of the partners by moderate coil currents requires a weaker main pole field. In addition, the micro-magnetic polarization conditions that actually arise in the sleeve 2 are difficult to quantitatively determine and cannot be controlled in detail by the macroscopic coil field attacking "from the outside".

With regard to the energy requirement, the electrical switching times of the arrangement must also be taken into account. The field of the plate-shaped main pole 1b moving away from the sleeve 2 must be so weak that it can no longer switch the sleeve material if the support of the repulsive coil magnetic field is no longer available after the coil current is switched off. In the active case (actuator operation), the typical rise time of the coil current is approx. 300µs, corresponding to the inductance of the coil 3 used (typical dimensions: outer diameter 3.2mm, length 4mm, approx. 250 turns) with a typical control voltage of approx. 30V. For the reliable function of the actuator dimensioned in this way, only approx. 3A coil current with a duty cycle of approx. 1ms is required.

In the passive case (operation of the arrangement as a tactile input unit, trivially the tactile pin must then be in the "up" position) the physical relationships of electromagnetic induction apply: depending on the rate of the magnetic flux change through the coil - caused by the movement of the main pole 1b and auxiliary pole 1a when the coupled tactile pin is pressed down - an electrical potential difference is established across the coil ends. With the dynamics of a tactile finger pressure, induction voltages of approx. 35mV can be achieved in this way. The temporal pulse shape is relatively complex, consisting of the basic course corresponding to the purely mechanical-tactile movement rate and a lower level, higher frequency component. Presumably, two parallel processes are used here: on the one hand, the magnetization of the sleeve 2 is reduced overall by the "slow" spatial removal of the plate-shaped main pole 1b (relaxation of the domain magnetization involved to its original orientation of the easy magnetic axis) and, in addition, the auxiliary pole 1a begins to remagnetize the first domains of the sleeve material when it is simultaneously exchanged for the upper part of the sleeve 2. Due to the micro-magnetic shape anisotropy of the materials used, this reversal of the local domain magnetization only occurs above a certain field threshold, but then "suddenly", which explains the high-frequency pulse component. When the tactile pin is released, it springs back to the originally set "up" position, as is necessary for the continued correct display of the data (= set braille pins) for the actuator in output mode. The voltage peak when released tends to be around 20% higher, with increased high-frequency components when the main pole 1b "hits" the front face of the sleeve. When using a suitable electrical detection technology (in particular a "partial response" detection, as is common in magnetic storage when reading HDDs), the bistable actuator according to the invention can also be used as an input unit. Thanks to the matrix control of the coils, even the position of the pressed pin is known. This makes it surprisingly easy to simulate a mouse cursor on the tactile display and to implement a 1:1 transfer of the screen-oriented working method to the tactile domain of the blind PC user on the computer.

These findings are the reasons for the novel, special design of the pole shapes of the actuator in the tactile application presented. The group of representations 2 B , 2c , 2d and 2e shows the effect of this special contour of main pole/plate 1b and sleeve 2 on the magnetic fields compared to a simple cylinder shape with 1:1 size fit of the diameters of plate 1b and sleeve 2 as in 2a shown. There, the (strong) stray field 4 of the main pole 1b is only symbolically represented by the strength and lateral position of the curved double arrow. One can imagine, for example, that this is approximately the spatial extent up to which the (strong) stray field 4 of the main pole 1b would still be able to dominantly magnetize the low-coercivity material of the sleeve 2 despite the presence of the coil field. W1 and w2 indicate this spatial extent of the corresponding stray fields 4 and 4cd, respectively. W1 is significantly larger than w2. The physical background is only shown purely qualitatively in order to illustrate the special effects of the pole contours.

If one considers only the holding force in the “up” position, the design of the 2a in terms of holding force as the optimal solution for tactile application. However, the magnetization, force and field conditions of the components involved, sleeve 2, rod 1, plate 1b and energized coil 3, require in the switching case (see situation 1a to situation 1b) a precisely calculated reduction of this maximum holding force, which is achieved by adjusting the diameter ratio of plate 1a and collar of the sleeve 2, which is widened at one end. It can be seen how the (strong) edge fields (stray fields) 4 of plate 1b in the case of 2 B “reaching into the void”, while in 2a It is precisely because of these edge fields that the maximum attraction force between plate 1b and sleeve 2 is achieved. The technical implementation now shows that with reasonable coil currents (e.g. less than 3A) no sufficient counterforce for detachment can be generated if a moderate coil current and the sleeve magnetization are to initiate a downward movement of the rod 1.

The conical special design of the plate 1b in 2c causes exactly this reduction of the maximum holding field and also ensures a clear, targeted reduction of the magnetic stray field 4cd to one or more other neighboring actuators, which are not shown in the illustrations for reasons of clarity. Both contour measures can be used together in the technical implementation depending on the current field conditions (due, for example, to details of the magnetic material used and the distance ratios between the pins of neighboring actuators) ( 2d , where the plate 1b is designed as a truncated cone, 2e where an alternative stepped design of the contour is shown), but can also be used individually ( 2 B , 2c ).

In 3 the arrangement according to the invention is shown at the upper stable operating point, without current flowing through the coil 3. The magnetizations of sleeve 2 and rod 1 relevant here are shown schematically.

In 4 the specific effects of the described contouring measures of the poles are shown for various geometric combinations. Coercive field strengths and saturation magnetizations of the rod and sleeve material combination (1, 2) were (9700 A/cm at 1.2 Tesla) and (480 A/cm at 1.38 Tesla), respectively. The "counterforce", which must be negative for the downward movement of the rod 1, is plotted against the (positive) holding force achieved in the stable "up" position. Using a plate 1b with a diameter of 3.3 mm and a height of 1.5 mm, the best holding force is 1.75 N. However, the arrangement is not usable because when remagnetizing (3A current) a positive, i.e. upward, counterforce is created: the plate 1b remains stuck to the sleeve 2.

Purely scale-technical measures (diameter 3.0 mm and height 1.0 mm) do not bring the arrangement into the functional range (in 4 indicated by the open arrow pointing from the large square symbol to the smaller one). Only the described contour measures for the poles bring the desired negative values for the counterforce, combined with an acceptable, slight reduction in the holding force, as shown by the thick black arrows. The two lower arrows show the effect of the diameter reduction of the sleeve collar (by 30% and 50% respectively), while the upper thick arrow (to the triangular symbol) demonstrates the effect of the cone contouring of the main pole 1b. The (further) reduction in the holding force is understandable, but in use the advantage of the lower stray field to neighboring actuators outweighs this, as with 2c , 2d already described.

As in 5 shown in a simplified cross-section using the example of two actuator levels 13a and 13b, the individual axial actuators A are arranged two-dimensionally - offset parallel to the pin-plate level 12 with pins 11 of the surface display. The working direction of the individual actuators A and the plane of the pin-plate 12 are perpendicular to each other. The force-fit connection of the individual actuator A to the tactile pin 11 is brought about via the lower part 14a and 14b of the tactile pin 11, which has a tapered diameter. If the actual tactile pin 11 and its tapered lower part 14a or 14b are designed as physically and materially separate parts, it is sufficient to provide one type of tactile pin 11 with the large nominal diameter, but otherwise the same length, for both actuator levels 13a and 13b. In this representation of the basic principle using only 2 actuator levels 13a and 13b, the lowest level of the control ICs has not yet been drawn in for reasons of clarity.

6 shows the hole pattern according to the arrangement 5 in the top view of the upper actuator level 13a, whereby the pin plate 12 with pins 11 above is only indicated at the edge of the drawing. A denotes the mounting position of the individual actuator A. The through holes 15 for the tapered actuating part of the pins 14b of the actuator level 13b below are arranged in accordance with the required grid dimension d. One can see the basic possibility of mounting individual actuators with a lateral dimension larger than the specified grid dimension.

7 shows the principle of the grid pattern of four actuator levels 13a to 13d in an x-y coordinate system in a top view. The grid dimensions can in principle be different in the x and y directions, as indicated by the designation dx and dy. It can be seen that for all levels 13a to 13d identical 4-position basic patterns are arranged at twice the distance of the pin-plate grid dx and dy, laterally shifted in the x and y directions depending on the actuator level, so that ultimately all grid points of the top pin plate 12 (not shown here) can be covered. In the narrow pin grid (dx and dy) in practically every level, except for the lowest level 14d, there are through holes for the actuating rods 14a, 14b, 14c, 14d of the respective lower levels. Due to the tapered diameter of the actuating part of the pins, their diameter can be designed in such a way that the greatest possible free space is available for the actuators A in the relevant plane.

You can find in 8th the schematic oblique sketch of the entire stack arrangement for the maximum case of 4 actuator levels. For reasons of clarity, actuator positions are only drawn here for the outer actuators of levels 13a and 13b. In levels 13c and 13d, the corresponding positions start one grid spacing further inside the respective level. The positions are occupied accordingly 7 : for example, for the lowest level 13d at the positions of the octagon symbols. Level 16, in which the integrated circuits are mounted, completes the display at the bottom.

It is advantageous to use proven printed circuit board technologies for the production of the actuator levels 13a to 13d, with the help of which in particular In particular, the numerous openings in the actuator plates can be manufactured automatically and cost-effectively. The provision of the necessary wiring for actuator control (regardless of which actuator type is actually used) is thus guaranteed by a well-established manufacturing process. Finally, the space on the levels free of openings makes it easy to have the electrical connections (not shown) between the levels up to the circuit level 16 run perpendicular to the pin plate 12, similar to the mechanical connections between pin 11 and individual actuator A.

9 shows the purely geometric background of the contamination situation. For reasons of clarity, the principle is sketched, so there is no scale accuracy. The vertically moving tactile pin 21 slides in the pin plate 12, driven by the actuator A underneath, whose fixed structure is designated 23. Whether A is the actual actuator (e.g. a piezo element) or the functional surface of a mechanical unit attached to the actuator (e.g. a toggle lever gear) is irrelevant for the following consideration. The vertical linear movement of both units is symbolized by the double arrow.

The omnipresent dirt particles 24a penetrate into the interior of the display, as indicated by the small arrows on the particles. They either settle directly 24b in the space between pin 21 and pin plate 12, where they immediately hinder the pin movement, or over the course of the operating time of the display they even reach the area around the functional area of actuator A, where they initially accumulate, see 24c. From this point they can later cause massive disruption to the actuator itself, see 24e.

The invention now makes it possible to minimize both the size spectrum and the amount of dirt particles 24c deposited in the environment of the actuator A. This is achieved by attaching the 10 shown dirt shield 25 in conjunction with the use of an actuating rod 26 for the pin 21, the diameter of which is smaller than that of the tactile pin 11. The dirt shield 25 can be designed as a solid part (e.g. as a sheet metal plate with holes) or as a flexible film that tightly encloses the actuating rod 26. Due to the smaller diameter of the actuating rod 26 compared to the pin 21, the film solution results in significantly lower inhibiting forces for the vertical movement even with a tight, cuff-like enclosure, because the rubbing contact surfaces are significantly smaller than when the actual pin is enclosed.

To remove the dirt particles accumulated during operation, the single tactile pin 21 with its actuating rod 26 can be easily removed from the outside by the user, as shown in 11 shown by the curved arrow. The mechanical coupling of the actuating rod 26 to the actuator A is preferably carried out by magnetic coupling of the two. The actuating rod 26 itself is soft magnetic. The actuator A itself, on the other hand, is designed as a complete hard magnet, as in 13a shown: The actuating rod 26 is magnetically coupled in a laterally central position to the front surface 27 of the actuator A. The decisive factor is the possibility for the user to easily separate the individual pin 21 from the actuator A by intervention from the outside in order to later reposition it without any problems after cleaning.

In principle, this procedure is also possible through mechanical coupling measures between the actuating rod 26 and actuator A (e.g. click connections, rotary locks). However, the increased design effort for mechanical solutions is to be viewed very critically, especially due to the manufacturing problems in connection with the accuracy of fit between the pin plate 12, actuating rod 26 and actuator A: Self-adjustment of the contact position of the soft magnetic actuating pin 26 on the front surface 27 of the hard magnetic actuator A, as in the magnetic solution (magnetic coupling) in 13b shown shortly before coupling, does not occur with mechanical connections. The double arrow shows the lateral play when inserting the pin unit 11. For reasons of clarity, the tactile pin 11, which is firmly connected to the actuating rod 26, is not shown here.

In 12 an embodiment of the invention is shown in which the dirt cover 25 of the 10 by suitable geometric design of the openings is structurally integrated directly into the pin plate 12 itself.

Especially the magnetic-mechanical self-adjustment of the pin unit is shown in Fig. 13a and 13b The soft magnetic material of the actuating rod 26 reacts to the presence of the spatially close hard magnet by forming induced magnetic poles, as highlighted by the designation N and S. This arrangement allows the geometric fit of the pin 11 in the guide of the perforated plate 12 - see here eg 12 - to go to the limits of the part tolerances, so that around the pin 21 a A very narrow gap is created, which optimally reduces the probability of dirt particles 24a penetrating into the interior of the display.

14 shows the basic structure and wiring of a coil matrix for the active actuator function. The coils are labeled 3, the moving cores K. The components required for correct electrical function are labeled T (for TRIAC) and C (for capacitor). For reasons of clarity, only a 3x3 arrangement is shown in detail and the detailed control of the TRIAC gate is not shown. However, the arrangement can be extended as desired, as indicated by the dots/stars and the label "etc.".

The address lines for the horizontal row supply are designated Za, those for the vertical column supply Sb. The respective numbering index Hi or Vi is in principle unlimited. The vertical and horizontal lines carry the current for the coil current supply. The driver output stages (designated Ta and Tb) can be set to high potential (V+), low potential (V-), or to a high-impedance state HI. If, for example, the second coil at the top is to be supplied with current, the address line V1 is set to (V+) and at the same time the address line H2 is set to (V-). All other Vi and Hi lines indexed with "i" assume the high-impedance initial state. Thus, in the example shown, only the coil with the coordinates (2; 1) is supplied with current. The actuator A reacts by moving its hard magnetic core K, as indicated by the double arrow. All other coils in the matrix do not "see" any potential difference at their end connections, and are therefore mechanically passive. If the coil current is to act in the opposite direction, and the actuator movement is to run in the opposite direction, the applied voltages of the selected coil are swapped between the respective H and V lines.

15 shows the wiring of the coil matrix in the high-impedance input state of the device. The drivers Ta, Tb of all horizontal and vertical lines Hi and Vi are in the high-impedance HI state. If the movable hard magnetic core K of a coil 3 is moved (the pressure movement of the finger is shown by the downward arrow), it generates an induction voltage in the coil. The specific Hi and Li lines (the case with the coordinates (1; 1) is shown here) are then at an electrical potential corresponding to the change in magnetic flux. Electrical circuits already known from magnetic data storage for optimal temporal signal shaping and signal detection of inductive voltage curves (these can be, for example, suitable diode / capacitor combinations, peak value detectors, integrators and threshold discriminators) are shown as blocks "SF". However, for reasons of clarity of the illustration, these are not shown in detail with their special functions.

The address adr. of the affected multiplexer input in the case of a certain actuator core K that is currently being manually operated can therefore be identified and transmitted asynchronously to a control unit CPU, for example by triggering an interrupt. However, it is also possible for the control unit CPU itself to address the multiplexers MUXa, MUXb synchronously and then successively query the multiplexer inputs at the output of the respective multiplexer MUXa, MUXb. In the specific design, it can also be advantageous in terms of signal technology to carry out the signal shaping SF before the inputs of the multiplexers MUXa, MUXb, but this has the disadvantage of using more components. In practical implementation, it can also be advantageous to connect several actuators in parallel, or to use only a certain reduced number of actuators A (e.g. every fourth in a row and/or column) for the passive detection function of the coil matrix.

The 16 to 22 show an application of the invention as an intuitively usable optical-tactile visual aid. 16 shows the block arrangement of the intuitive visual aid. A digital camera 51 can be designed as a full-area camera or a line camera (“scanner”). The image signals 52a are fed to a data processing device 53. This can be a personal computer, a digital signal processor, a CPU or a microprocessor. The software of the data processing device 53 meets the requirements of data reduction with image recognition. The software also divides the image into areas with different tactile point resolutions and different tactile image refresh rates and forwards the corresponding image signals 52b to a tactile device 54. The advantage of this splitting measure is that the blind person can, for example, scan the outer area of a tactile image very quickly without being distracted from important information by detailed representations elsewhere. Think here, for example, of a fast-running person suddenly crossing the path vertically. Here, the exact contour of the person or even the information man/woman is initially completely unimportant, the fact of the sudden appearance of an obstacle must be quickly felt. The difference between image signal 52a and signal 52b in terms of pulse density and pulse number outlined in the illustration is intended to make it clear that signal 52b is a data-reduced signal compared to the original image source/digital camera 51.

In 16 the tactile device is shown as a surface display with a constant grid spacing of the tactile points. In contrast, in 17 an embodiment of the tactile output unit 54 with a geometrically non-uniform point grid is shown. The arrangement of the grid areas with different resolutions is preferably centrally symmetrical to the center of the image in order to approximately simulate the function of the "foveal vision" of the human visual sense in a tactile manner.

18 shows a possible embodiment in which the camera 51, data processing 53 and tactile output unit/display 54 are arranged in one housing. The different heights of the individual tactile positions of the display 54 schematically show a set/replaced state. In principle, the housing can be used both mobile and stationary. The stationary version with a camera 51 with area sensor is conceivable, for example, for installation in the desk of a blind clerk who often has to communicate with people sitting or standing opposite him.

In contrast, 19 a possible variant with a built-in line camera / scanner 51 for optical-tactile scanning of flat graphic templates. The double arrow symbolizes the mechanical travel path of the line camera / scanner 51. For reasons of clarity, lighting devices, mechanical guides and electrical connections between the individual components are not shown. This line scan variant can of course also be implemented as a mobile device.

20 shows a special mobile variant that uses the hardware and software of, for example, an intelligent mobile phone already available to the user, a "smartphone" 56a with a screen 56b and a built-in camera 51. Here, the tactile display 54 is simply placed on the existing screen 56b of the smartphone 56a, as indicated by the curved double arrow. This variant can be designed in such a way that the tactile display 54 can also be placed or removed by the user at any time. The use of a smartphone 56a is particularly advantageous because, with suitable software programs ("apps"), both the existing hardware (central processor) for data processing and the optical screen of the smartphone can be used directly as an optical output device for the image patterns 58b to be displayed in the tactile display 54. In the embodiment shown, the 20 The tactile display 54 is controlled without any additional wiring effort, in a quasi “contact process”, which is done via opto-electronic components 57 in the tactile device, which scan the optical screen pattern 58a.

For reasons of clarity, only the optical receiver 57 for a single active transmit image element of the smartphone display 56b is shown in the figure. The optoelectronic connection is of course not mandatory: The connection plug for data exchange/power supply already present in the smartphone can certainly be used to establish the signal exchange - and possibly also the power supply.

21 shows the side view of the assembled arrangement according to 20 . It is clearly visible how flat and compact the optical-tactile visual aid can be designed in this mobile embodiment. The set/unset tactile pins for the image pattern 58b to be displayed are shown purely schematically in terms of their height only to clarify their display function: In the practical embodiment, the unset pins will not protrude beyond the left surface of the tactile display 54, for example.

Of course, instead of an existing smartphone with camera 56a, 56b, 51, a special camera - preferably equipped with an extremely wide-angle lens - can be used. Accordingly, the telephone 56a and its screen 56b are then to be replaced by a housing with a built-in data processing unit 53 and power supply. This shows 22 .

The camera 51 is shown next to the tactile display 54 with the data processing device 53 integrated into the housing of the display. The camera 51 can be attached to clothing, for example at shirt collar height, or worn on the head in a manner similar to glasses. The tactile display 54 can be worn on the thigh using a belt for convenient use, for example, or can be carried discreetly hidden in a trouser or jacket pocket.

In the embodiment shown, the housing of the tactile display 54 also houses all other devices for data processing 53. The connecting line 59 shown between the camera 51 and the parts 53 and 54 carried in the trouser pocket, for example, can in principle be designed as a cable connection, but for more convenient use of the device, a wireless data connection is preferable. Depending on aspects relating to data and eavesdropping security, ity of the entire device as well as the power supply of the camera 51, one of the two alternative solutions will be implemented.

Furthermore, the invention is not limited to the combinations of features defined in patent claims 1, 5, 14 and 20, but can also be defined by any other combination of specific features of all the individual features disclosed overall. This means that in principle practically every individual feature of patent claims 1, 5, 14 and 20 can be omitted or replaced by at least one individual feature disclosed elsewhere in the application.

List of reference symbols:

1

Rod (linear freely movable, hard magnetic)

1a

Auxiliary pole (upper end of rod 1)

1b

Main pole (plate-shaped)

2

Sleeve (hard magnetic)

2a

collar-shaped extension (of sleeve 2)

3

Kitchen sink

4

Stray field (of the main pole 1b)

4cd

Stray field (of the main pole 1b, weaker)

11

Pen

12

Pin plate

13a

Actuator level

13b

Actuator level

13c

Actuator level

13d

Actuator level

14a

tapered lower part (tactile pin 11)

14b

tapered lower part (tactile pin 11)

14c

tapered lower part (tactile pin 11)

14d

tapered lower part (tactile pin 11)

15

Through hole (for tapered actuating part 14b)

16

Circuit level

23

Structure (of actuator A)

24a

Pollution particles

24b

Pollution particles

24c

Pollution particles

24e

Pollution particles

25

Dirt shield

26

Actuating rod

27

Frontal area

51

digital camera

52a

Image signals (of the digital camera 51)

52b

Image signals (of the digital camera 51)

53

Data processing device (CPU, signal processor, etc.)

54

tactile device (output unit, display)

56a

smartphones

56b

Screen (of smartphone 56a)

57

opto-electronic component (optical receiver)

58a

Screen pattern

58b

Screen pattern

59

Connecting line

A

Actuator (mounting position)

adr.

Address line (multiplexer input)

C

capacitor

CPU

Control unit

d

Grid dimension

H

Projection (of auxiliary pole 1a)

H1

Thickness (of main pole 1b)

Hi

Horizontal - line (current for the coil power supply)

HI

high-resistance state

K

Core (of coil 3)

MUX

multiplexer

MUXb

multiplexer

N

North Pole

S

South Pole

Sp

Address line (vertical column)

SF

Block (circuit for temporal signal shaping and signal detection)

T

Triac

Ta

Driver power amplifier

Tb

Driver power amplifier

Vi

Vertical line (current for coil power supply)

W1

spatial extent (of the scattered field 4)

w2

spatial extent (of the scattered field 4cd)

Za

Address line (horizontal line)

Claims (19)

Magnetically bistable axially symmetrical linear actuator (A) for tactile applications with a hard magnetic rod (1) which is widened at one end in a plate-like manner (1b) and with a coil (3) arranged on a circuit board in which the rod (1) is freely movable in the axial direction, characterized in that the rod (1) consists of a material with a very high coercive field strength, that it is axially enclosed by a hard magnetic sleeve (2) of at most the same length with a significantly lower coercive field strength and is freely movable in the axial direction and that the travel of the rod (1) is determined by its excess length (h) in comparison to the length of the hard magnetic sleeve (2), such that an auxiliary pole (1a) is formed at one end of the rod (1) and a plate-like main pole (1b) is formed at the opposite end and that the coil (3 - comprising several turns - completely surrounds the sleeve (2), whereby only the sleeve (2) and not the rod (1) can be reversed and a bistable linear movement of the rod (1) is achieved. Actuator after Claim 1 , characterized in that the main pole (1b) has the contour of a cone or a truncated cone or a truncated cone with a disk-shaped base as a plate-like extension, wherein the height (H1) of the cone or the truncated cone or the height (H2) of the plate-like extension of the rod (1) causes the stray field (4, 4cd) of the plate-like main pole (1b) in the "down" position of the actuator to no longer be able to switch the magnetization of the sleeve (2). Actuator according to one or more of the Claims 1 until 2 , characterized in that one end of the hard magnetic sleeve (2) has a collar-shaped extension (2a), the diameter of which is dimensioned such that the collar-shaped extension (2a) covers the adjacent end face of the enclosing coil (3) at least partially, at most 95% of the diameter value of the plate-like main pole (1b) of the hard magnetic rod (1). Actuator according to one or more of the Claims 1 until 3 , characterized in that the ratio of the said coercive field strengths of the two hard magnetic materials of rod (1) and sleeve (2) reaches at least the value 3:1, so that the axial magnetic field of the coil (3), which encloses rod (1) and sleeve (2) together, only switches the material of the sleeve (2) but not that of the rod (1) in the magnetic polarity. Device for arranging axial actuators according to Claim 1 in a tactile display with a pin plate (12) and pins (11) according to one of the preceding claims, characterized in that the actuators (A) are arranged in at least two and a maximum of four planes (13a, 13b, 13c, 13d) running parallel to the pin plate (12) of the display and staggered vertically such that the lateral mutual distances of the actuators (A) in one plane are greater than the grid dimension (d) specified for the pin plate (12). Device according to Claim 5 , characterized in that the tactile pin (11) has its maximum nominal diameter only in the region of the guide surfaces of the pin plate (12) and tapers in diameter (14a, 14b, 14c, 14d) below the pin plate (12). Device according to one or more of the Claims 5 until 6 , characterized in that the actuator levels (13a, 13b, 13c, 13d) are provided with narrow through-holes exactly in the grid dimension of the pin plate (12). Device according to one or more of the Claims 5 until 7 , characterized in that, with identical lengths of the actual tactile pins (11) with nominal diameter, at least two and at most four types of actuating rods tapered in comparison to the nominal pin diameter with two to a maximum of four different lengths are used. Device according to one or more of the Claims 6 until 8th , characterized in that the actuator levels (13a, 13b, 13c, 13d) are designed as electrical circuit boards or as multi-layer circuit boards. Device according to one or more of the Claims 6 until 9 , characterized in that one or more additional circuit boards with electrical components (IC's) are attached as the lower end of the device. Device according to one or more of the Claims 6 until 10 , characterized in that for reliable operation of the movable stylus pins (11) a mechanical dirt shield (25) is arranged below the level of the pin plate (12), which minimizes the penetration of dirt particles (24a) into the interior by geometric shading. Device according to one or more of the Claims 6 until 11 , characterized in that the stylus (11) is firmly connected at one end to an actuating rod (26), whose diameter is at most half the diameter of the stylus (11). Device according to one or more of the Claims 6 until 12 , characterized in that the thin actuating rod (26) is made of soft magnetic material and is coupled to the end face (27) of the hard magnetic actuator (A) by means of magnetic forces, wherein a self-adjustment of the contact position of the soft magnetic actuating rod (26) on the end face (27) of the hard magnetic actuator (A) takes place shortly before coupling. Switching matrix for controlling row and column connected coils in a device according to Claim 5 , characterized in that the coils (3) each have a hard magnetic axially movable core (K) in the interior, and thus the individual coil (3) can function both passively as a sensor via electromagnetic induction by mechanical displacement of the hard magnetic core, and mechanically actively as an actuator by means of targeted energization of the coil (3). Switching matrix according to one or more of the Claims 6 until 14 , characterized in that the row and column current supply to the coils (3) is carried out by electrically bipolar power output stages (Ta, Tb), which additionally have a third, high-impedance switching state (HI). Switching matrix according to one or more of the Claims 6 until 15 , characterized in that in the case of the high-impedance switching state (HI) of the switching matrix, one or more analog multiplex switches (MUXa, MUXb) are additionally electrically connected to the column (Sp) and row lines (Za) of the switching matrix, thus making it possible to provide the differential voltage between selected column and row lines at an analog output of the multiplex switch (MUXa, MUXb). Switching matrix according to one or more of the Claims 6 until 16 , characterized in that the supply lines to the input of the analog multiplex switch (MUXa, MUXb) are each provided with a signal shaping (SF) which conditions the induced voltage signal for further digital processing and use, and that the output of the analog multiplex switch (MUXa, MUXb) is connected to a signal shaping (SF) which conditions the induced voltage signal for further digital processing and use. Switching matrix according to one or more of the Claims 6 until 17 , characterized in that the signal-shaped output signal of the multiplexer (MUXa, MUXb) can trigger an interrupt in a downstream control unit (CPU) which is asynchronous to the clock of the control unit (CPU) and that the row and column addresses of the analog multiplex switch (MUXa, MUXb) present at the time of the asynchronous interrupt are transferred to the control unit (CPU). Switching matrix according to one or more of the Claims 6 until 18 , characterized in that the control unit (CPU) itself generates the row and column addresses of the analog multiplex switch (MUXa, MUXb) synchronously.

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